Improvement in balance slide-valves



-" I 11ml 5 tutta @utenti WILLIAM M. STEVENSON, O-F SHARON, PENNSYLVANIA;

' Leners PatentNo. 83,336, daedoctab@ 20,1scsf` y e v IMPROVEMENT INBALANCE SIIEIIDI'EVi-VAIIII'VIElS.

\ The v Schedule referred to these Letters Patent and making part of the same.

To all 'whom it oa/y concern:

Be it known that I, WILLIAM M. S'rEvnNsoN, of

' Sharon, in the, county of Mercer, and State of Pennsylvania, have invented certain new and useful Improvements in` Balance Steam-Cut-Oil Valves; and I do hereby declare that the following isa full, clear, and exact description thereof, reference 'being had to the accompanying drawings, and to theletters of reference marked thereon, which form a part of this specification, in which is represented a longitudinal section of my. invention. Y

The nature of my invention consists in an additional wall to the sides of a steam-valve, either on the outside or inside, lthese walls taking up the full width of Athe port-lap o1"v iiange that covers the ports.

. In order te enable others skilled in the art to make and use my invention, I will now proceed to describe y its construction and operation.

A--represents the steam-chest, made in any of the knownand usual Wa s.

a a' are the two walls which cover the openings() C inthe bottom of the'steamchest. Between these walls is a cavity, d, open both a't top and'bottom, which, as

shown in the drawing, is smaller at the bottom byabout one-half than at the top.

The walls are, at their tops, provided with grooves, in which Iinsert packing-strips e e. These strips are three-cornered, andunder them steam isadmitted,

through the holes o' fi, for the purpose k"of"adjusting them to the cap of the steam-chest, therebg'se-ating the valve, and allowing no steam to escape under or over the valve.

- The cavity d, between the' walls a a, is filled with steam when the same is 'let past the edgeof the valve into the ports or cylinder. The object of thisis to cause a downward pressure on the valveat the time there is an upward pressure, by steam,'in the ports on the exposed pa-rt 4of the port-lap, thus making the steam counterbalance itself at the most critical points f the j-travel of the valve. v

Having thus fully described my invention,

`What I claim as new, and desire to secureby Let- I ters Patent, is

A steam-valve, constructed as described, with a cavity, d, between the walls a a, 'and with packing-strips e e, in grooves on the top of the walls, steam being 

